The invention relates to an electric vehicle, in particular to a driving system for an electric vehicle.
With heavier and heavier environmental pollution, people pay more and more attention to environmental protection. Electric vehicles use or mainly use electric power to drive its wheels to rotate. Thus, it is expected that electric vehicles will be more widely used in near future because they are more environmentally friendly than the conventional vehicles. A commonly used driving system for an electric vehicle generally comprises a motor and a gearbox. Specially, the motor drives a wheel of the electric vehicle by means of the gearbox.
It is well-known that there are two common driving systems for electric vehicle: planetary gear in-wheel driving system and near wheel driving system. In a planetary gear in-wheel driving system, both the motor and the gearbox are disposed inside of a rim of the wheel of the electric vehicle, and the gears of the gearbox are disposed around an output shaft of the motor. In a near wheel driving system, both the motor and the gearbox are disposed outside of a rim of the wheel of the electric vehicle, and the motor is disposed to be offset to the gearbox. Compared with the near wheel driving system, the planetary gear in-wheel driving system has a compact size by disposing the motor and the gearbox in the same housing and a good balancing by distributing symmetrically the weight of the gears of the gearbox about the output shaft of the motor. The near wheel driving system can produce larger power density due to improved cooling performance and achieve a high efficiency. The near wheel driving system is often selected for high power vehicles due to its larger power density. However, in the existing near wheel driving system, the motor and the gearbox are disposed to be offset to each other so that the balancing of the near wheel driving system and thus the vehicles is very poor, which further cause difficulty in controlling the vehicles and degradation in riding comfort. Further, in the near wheel driving system, the motor and the gearbox substantially protrude outside of the wheel, which adversely affects the passing ability and the visual appearance of the vehicle. These problems are more obvious for the near wheel driving system with larger power density due to an increased size of the motor, especially for the near wheel driving system designed for an electric motorcycle (also referred to an electric scooter).
Thus, there is a need to make improvements on the existing driving system for the electric vehicle.